Technical Field
Embodiments of the present disclosure relate generally to load harmonic suppression. More specifically, embodiments relate to systems and methods for load harmonic suppression in uninterruptable power supplies (UPS).
Background Discussion
UPSs are generally constructed to isolate a load from disturbances in an external power source (e.g., a power grid). Various parameters may be measured to analyze the quality of the power output by the UPS to the load. For example, the total harmonic distortion (THD) of the output voltage waveform by the UPS may be determined. The THD parameter of a waveform compares the magnitude of the harmonics with the magnitude of the fundamental frequency present in the waveform. The harmonics are signals present in the waveform at integer multiple frequencies of the fundamental frequency. A large THD value indicates that the waveform is distorted while a low THD value indicates that the waveform is undistorted.
The voltage waveform output by a UPS may become distorted due to the characteristics of the load being supplied. In particular, switch-mode power supply (SMPS) loads draw current with a substantial amount of harmonics. SMPSs variably draw current while performing voltage regulation and subsequently distort the voltage waveform.